In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not to be taken as an admission that the document, act or item of knowledge or any combination thereof was at the priority date:                (a) part of common general knowledge; or        (b) known to be relevant to an attempt to solve any problem with which this specification is concerned.        
A herbicide composition typically has to be in a form from which it is available to act upon the target. If, for example, a herbicide composition is sprayed on a plant and the carrier evaporates, the herbicide can be left solid and essentially unavailable for uptake.
Whilst the following discussion concerns glyphosate, it is to be understood that the same principles apply to all lipophobic herbicides having an acidic moiety.
Glyphosate is a non-selective herbicide which is applied in aqueous solutions to control weeds in agricultural, industrial and domestic situations. There has also been development of crops which are resistant to herbicides, such as glyphosate and glufosinate, so that the herbicides may be used post emergent to protect the crop. In this specification, the term “glyphosate” refers to N-(phosphonomethyl)glycine CAS No. [1071-83-6]. Currently, glyphosate is neutralised by a base, such as isopropylamine, to allow it to be carried in an aqueous system.
Adjuvants are commonly used with these aqueous glyphosate compositions to improve the efficacy or induce other desirable properties. Adjuvants can be either formulated into commercial ready-to-use glyphosate-containing products or sold as additives to be added to the tank mix. These adjuvant materials include (i) surfactants and/or oils for wetting, spreading and spray retention, (ii) buffering agents and water conditioners for protecting the glyphosate and (iii) polymeric materials which may reduce spray drift.
Sometimes the adjuvant is lipophilic, such as petroleum oils, vegetable oils or esterified oils, and, in these circumstances, an emulsifying system is also typically necessary to enable the hydrophobic adjuvant to form an emulsion with the aqueous glyphosate composition. When used with lipophilic adjuvants and/or oil carriers, the glyphosate is expected to remain in the aqueous phase and may not fully benefit from the use of such a lipophilic adjuvant.
There have been attempts to improve the efficiency of glyphosate which include the use of higher molecular weight amines to form a salt with the glyphosate. However, most of these attempts with salts of higher molecular weight amines were focused on the conventional glyphosate application system wherein the product is diluted in water for use. The amines which are described in these attempts include primary, secondary and tertiary amines.
The authors are aware of only one attempt to form essentially non-aqueous compositions of herbicides and these compositions were intended for application by electrostatic spraying. This attempt teaches the preferred use of a stoichiometric amount of a primary alkyl amine having 13 to 17 carbon atoms to form a salt with the herbicide. It also teaches the use of a significant portion of a volatile polar solvent in the formation of the salt and the composition which is applied.
Current spray application technology enables the application of essentially non-aqueous agrochemical compositions as well as aqueous compositions. Oil-soluble (lipophilic) insecticides and herbicides can be diluted in lipophilic carriers, such as petroleum or vegetable-based oils for spraying rather than dilution in water. By choosing appropriate lipophilic carriers, some of the inefficiencies associated with aqueous spray mixtures, such as droplets reflecting off the target, in-flight evaporation and droplet dry-down, can be minimised. Rainfastness of the active may also be a problem for some products where the active constituent may be washed off the target by rain some hours after application but before it has been adequately taken up. Other benefits which may be achieved using non-aqueous carriers include enhanced uptake into the target and reduced spray volumes.
Herbicide compositions are also applied using planes or helicopters. Much of the cost of aerial spraying is associated with the aircraft set up and flying time, hence to be able to spray highly concentrated compositions over a larger area without reloading multiple times allows for more efficient use of aircraft.
Glyphosate and other lipophobic herbicides, such as glufosinate, are basically insoluble in lipophilic carriers which would allow exploitation of the lower spray volumes. Thus, there has been a need to develop an essentially non-aqueous carrier system with low volatility for a lipophobic herbicide such as glyphosate.